<p>Flexible and Transparent Artificial Synapse Devices Based on Thin-Film Transistors with Nanometer Thickness</p>

Abstract

Background: Artificial synaptic behaviors are necessary to investigate and implement since they are considered to be a new computing mechanism for the analysis of complex brain information. However, flexible and transparent artificial synapse devices based on thin-film transistors (TFTs) still need further research. Purpose: To study the application of flexible and transparent thin-film transistors with nanometer thickness on artificial synapses. Materials and Methods: Here, we report the design and fabrication of flexible and transparent artificial synapse devices based on TFTs with polyethylene terephthalate (PET) as the flexible substrate, indium tin oxide (ITO) as the gate and a polyvinyl alcohol (PVA) grid insulating layer as the gate insulation layer at room temperature. Results: The charge and discharge of the carriers in the flexible and transparent thin-film transistors with nanometer thickness can be used for artificial synaptic behavior. Conclusion: In summary, flexible and transparent thin-film transistors with nanometer thickness can be used as pressure and temperature sensors. Besides, inherent charge transfer characteristics of indium gallium zinc oxide semiconductors have been employed to study the biological synapse-like behaviors, including synaptic plasticity, excitatory postsynaptic current (EPSC), paired-pulse facilitation (PPF), and long-term memory (LTM). More precisely, the spike rate plasticity (SRDP), one representative synaptic plasticity, has been demonstrated. Such TFTs are interesting for building future neuromorphic systems and provide a possibility to act as fundamental blocks for neuromorphic system applications.

Full-Inorganic Flexible Ag2S Memristor with Interface Resistance–Switching for Energy-Efficient Computing

“…More importantly, the switching energy of interface RS in our device is indeed much smaller than the reported FM based on filament RS. As summarized in Figure c, the pulse energy required to trigger interface RS with different ON/OFF ratios is benchmarked with recently reported filamentary FMs, ,,− where a reduction of switching energy by several orders of magnitude is achieved. An ultralow switching energy of only ∼0.2 fJ is needed to achieve a 5 ON/OFF ratio with the interface RS in our Ag 2 S FM (see the calculation details of switching energy in SI Figure S3).…”

Ultrasensitive Freestanding and Mechanically Durable Artificial Synapse with Attojoule Power Based on Na‐Salt Doped Polymer for Biocompatible Neuromorphic Interface

“…In a similar way, monophasic PSC induced by subthreshold stimuli in the form of either EPSC or IPSC, is widely emulated by various synaptic devices. [41][42][43][44][45][46][47][48][49][50][51] However, biphasic PSC triggered by suprathreshold stimuli is hardly implemented by artificial synaptic electronics. Nevertheless, as depicted in Figure 2a, the fabricated devices with NaAc doped PVA electrolyte exhibit biphasic PSC under a single spike with 1 mV amplitude and 100 ms width.…”

“…This is also consistent with other works based on pristine PVA which operated at several volts. [41][42][43][44][45] As one of the most essential metrics of the neural network, energy efficiency must be considered in the evaluation of artificial synapses. Here, E = IVt is used to calculate energy consumption, where I is activated PSC, V is spike amplitude and t is spike duration.…”

“…[32][33][34][35][36] Moreover, by virtue of NaAc-doping, it demonstrates an effective approach to reducing high stimulation voltage associated with PVA-based devices (blue area). [41][42][43][44][45] Even compared to other low-power artificial synapses with energy consumption comparable to that of biological synapses (yellow area), [47][48][49][50][51] NaAc doped PVA synaptic devices excel in terms of high sensitivity with 1-mV voltage.…”

“…Besides, PVA with excellent flexible property and biological compatibility possess promise in building sensory synapses and electronic sensorimotor nerves. [40] Given those superior merits, PVA has been exploited in electrochemical synaptic transistors as protonconducting electrolytes, [41][42][43][44][45] or served as an active layer in the synaptic resistive switching device. [46] Despite successful emulation of synaptic behaviors, similar problems perplex these artificial synapses, which stimulate at high spike voltage (≈1.5-9 V) and consume a large amount of power (≈7.29 pJ-3.75 uJ).…”